The primary field of application for this invention is to guidance of unmanned aerial vehicles (UAVs). A common characteristic among unmanned aerial vehicles is that they are capable of flying at air speeds that are marginally greater than winds speeds that are commonly encountered when flying at a low altitude and/or close to the ground, or around nearby buildings when flown in an urban environment. In such situations, a critical issue is maintaining an intended maneuver (such as flying a precise turn or circling over a target site), flying through confined air space, or maintaining a formation with respect to another air vehicle (for purposes of collision avoidance).
Ideally a guidance system in such cases should be as robust as possible in its ability to reject the disturbing effects of winds and wind gusts using only GPS data. Presented herewith is a method for precise circling about a target site based on the concept of minimizing the relative degree of the output being regulated, which is an improvement over current guidance strategy. These concepts are generally applicable to other guidance objectives as well.